I have done it, I have the power!

Btw. I could not find answer anywhere .. can two uncorrelated light power be simply added together ? Would they not interfere ? For example with sound and other noise signals you can't simply add them. Generally the rule is c^2=a^2+b^2, instead of c=a+b.
Does this apply to light too ? I can see it is a bit different, but can't find any details anywhere.

DrSid said:

Btw. I could not find answer anywhere .. can two uncorrelated light power be simply added together ? Would they not interfere ? For example with sound and other noise signals you can't simply add them. Generally the rule is c^2=a^2+b^2, instead of c=a+b.
Does this apply to light too ? I can see it is a bit different, but can't find any details anywhere.

Click to expand...

lasers isnt this all about light amplification ?

Dave 300 said:

lasers isnt this all about light amplification ?

Click to expand...

As long as you are inside single cavity, yes (and no). What lasers are about, is synchronizing the photons .. so they never cancel each other.
But when you have 2 lasers, and it is pretty hard to have them absolutely same and constant wavelength and same phase, some interference will appear. If the wavelength and phase changes rapidly (which is the case here), you can thought about the individual lasers as random phase radiation sources. And IMHO you won't get 2 watts from two 1 watt lasers (in the simple configuration, I think you could avoid interference by using different polarization for each laser .. but that would be impossible for more then 2 lasers).

Can someone with LPM and 2 similar powered lasers check this ? Just shine both lasers at the same spot, and get the resulting power ? I did a small numeric test and it seems that the result would be only 1.25x single laser power. Though my mathematical sense says it should be square root of 2. This looks more like cube root of 2. Can't find the error though.

I just saw this and watched the video.Epic.I strongly support this kind of gonzo science!
Excellent work!

Pontiacg5 said:

For real? Are you serious? You must just be stupid...

These are being direct driven off of the casio projector. I did nothing to them that the projector doesn't do under normal operating circumstances.

Click to expand...

Well, that's good to hear. Amazing how the projector pumps 1.8A to each diode by default... these things must be able to be pushed to 3w and beyond if that is the case. Cause at 1.8A and the projector being rated for 20,000 some odd hours.. heck, these diodes must be able to reach 5W if that is the case.

Oh, the blind sopt is looking rather well, in fact I can't even tell that its there because its not. If you actually know what to look for you can see that I use the back curve of the can, all of the reflections are directed at the wall, you can even see them there if you watch close enough.

You are obviously an idiot who thinks he knows something. I, however, have been doing stuff like this for 5 years. I know what I'm doing, how to control reflections, what to watch for, etc. Before you come in my thread trying to lecture me you'd best know what the hell you are talking about.

I believe a - rep is in order here.

Click to expand...

So you did look directly at the spot you were burning. Wow... just wow. That is about the most moronic thing anybody could do. Whether the reflections were aimed towards the wall or not, looking at a laser dot that is 24W+ is just flat out foolish and idiotic. You may have been doing this for a while, but looking directly at a 24watt laser under any circumstances is foolish. Heck, doing it with a 500mW laser is bad enough... let alone a machine outputting 48 times that power.

Oh and reflection towards the wall means nothing... once that can starts burning, the shape of the metal will change and it can throw reflections in any direction. Just admit it, what you did was flat out idiotic. And the fact you did that with this incredibly powerful beast of a laser, means you probably do it all the time with any other powerful lasers you use. I bet you have tons of blind spots from all the recklessness over the years.

Thanks for the -rep, but this will not change the fact that you are simply denying your reckless mishap and are just mad at me for calling you on it. You saying I am a idiot is such a irony... at least I am smart enough not to look directly at a 24 watt laser on a metal can.

drummerdimitri said:

Pontiac, could you please elaborate a little bit more about how you got that projector to lase in such a way? Did you disassemble it and that's it?

Click to expand...

The laser "block" with all the diodes and lenses is attached to a large knife
edge setup in the projector. Simply removing the assembly then reconnect
it to the circuit in the projector for power.

So I searched more .. and nobody really writes about combining incoherent light sources (only how to make them coherent so they can be simply added together).
I only found, that if someone professionally combines lasers, very special techniques are used (and yep, that idea of mine with polarization is used in some CO2 cutting lasers). Clearly nobody even thinks about simply focusing the beams at one spot.

I rechecked and improved my numeric model .. now it gives 1.27W for 2x1W lasers .. and 4.32W for 24x1W lasers.

And now somebody please tell me I'm at least in the right sport ..

Edit: this might be all wrong .. since the individual photons from each laser would have to arrive at the same moment .. and I totally can't estimate such thing.

Correct me if I'm wrong, but lasers are simply an energy transporting mechanism.

In order to produce just 4.3W from 24x1W lasers you'd have to generate 19.7W of waste heat. That excess energy has to go somewhere, and it definitely isn't being used to heat up the focusing lens, which is the only place that energy can escape in this system. It's far more efficient than that. Therefore you can assume that 24x1W lasers would put out 24W of energy minus whatever little was lost due to the focusing lens.

DrSid said:

Can someone with LPM and 2 similar powered lasers check this ?

Click to expand...

I get the sum of the two.

And yes, you need to consider conservation of energy. If the energy is so much less, where would the energy go?

Yep .. it seems to be all nonsense .. interference of two photons seems to be very rare, and even thought impossible for long time. Still I did not find any good explanation of this effect.
Most normal interference effects are achieved by photons interfering with themselves, and are visible only for lasers, because with lasers all the photons are similar, and the interference pattern is same all the time.
Anyway .. why then is this technique used more often ? Seems like simple way to achieve strong outputs.

Re: I have done it, I have tortured these diodes!

Pontiacg5 said:

I no longer have the strongest focal point

Its been dismantled and all diodes extracted. Can't keep the people waiting.

Expect more vids from the next projector. I need to prepare a place outside because the amount of smoke this thing puts off is nuts!

Click to expand...

Pontiacg5 said:

In the projector they are being driven at 1.8A for an output of each diode around 1690mW.

I got that info from HIMNL9, in this thread here http://laserpointerforums.com/f65/some-tests-made-a140-52516.html

Click to expand...

So while yes this is an interesting project, are these the diodes you are selling for $40 ea?

If im not mistaken, you have driven these 24 LD's at their max rated power for lengthy durations with no cooling provided by the 3 fans. The 3 fans provide well deserved cooling to the LD array when they are run at the intended setup.

In the video the array is placed on top of the projector being driven at its max output with no cooling other than a slight breeze coming from within the projector.

Add the increase of back reflection and exposure to smoke... Lets put it this way, I would not buy one of these LD's.

If you are going to sell these diodes, you should warn potential buyers of the abuse they were put through first. Perhaps sell them at reduced prices considering I have seen other members selling new and unused diodes for less.

You should change the title of this thread to 'how I tortured your LD before shipping it'





For unabused LD's, here is a good start > http://laserpointerforums.com/f55/casio-xj-a140-gb-38-50-shipped-us-54476.html < For the record, not my sales thread :beer:


*EDIT* Didnt see this prior to my post...

leukoplast said:

Also I kinda hope you told those buying these diodes that you were running them at such a high current and for such a lengthy period of time with this getup of yours. I mean I would hate to buy one of your diodes only to find out they only have about a hour of life left in them.

Click to expand...

"getup" just about sums it up. +1 Leukoplast, very valid point. Its unfortunate for the people buying, or have paid for these LD's.
Judging by the info on his sale page > http://www.lands.rice-precision.com/445nm_laser_diodes.html it would seem that people paid for these antics and noobish setup. I mean, if you are going to do something like this with other peoples diodes, at least do it right... still dont make it right, but hey..

The fans from the projector suck air in from the side and push it up and out over the diodes in this setup. The diode array gets hotter enclosed inside the projector than it does in the open air like that. The way the cooling is routed in the projector is horrible, but you wouldn't know that would you?

Increase in back reflection? To smoke? The diodes are encased in the knife edge array which is sealed. And on top of that the fans are pushing air AWAY from the diodes. There is no way smoke would be getting anywhere near these diodes. Also the beam would be so defocused and diffused if it just happened to be focused back at the diodes it would be nothing more than what and diode is normally exposed to.

So you did look directly at the spot you were burning. Wow... just wow. That is about the most moronic thing anybody could do. Whether the reflections were aimed towards the wall or not, looking at a laser dot that is 24W+ is just flat out foolish and idiotic. You may have been doing this for a while, but looking directly at a 24watt laser under any circumstances is foolish. Heck, doing it with a 500mW laser is bad enough... let alone a machine outputting 48 times that power.

Oh and reflection towards the wall means nothing... once that can starts burning, the shape of the metal will change and it can throw reflections in any direction. Just admit it, what you did was flat out idiotic. And the fact you did that with this incredibly powerful beast of a laser, means you probably do it all the time with any other powerful lasers you use. I bet you have tons of blind spots from all the recklessness over the years.

Thanks for the -rep, but this will not change the fact that you are simply denying your reckless mishap and are just mad at me for calling you on it. You saying I am a idiot is such a irony... at least I am smart enough not to look directly at a 24 watt laser on a metal can.

Click to expand...

As I told you before the beam was on the backside of the can I could not see the dot, I could only see the cone of beams being focused to a point. I was using that cone to get the can directly in the focal point. There is no physical way for that light to come anywhere near my face, no matter how much the can burns.


Opinions duly noted though, thanks for that!

Pontiacg5 said:

The fans from the projector suck air in from the side and push it up and out over the diodes in this setup. The diode array gets hotter enclosed inside the projector than it does in the open air like that. The way the cooling is routed in the projector is horrible, but you wouldn't know that would you?

Increase in back reflection? To smoke? The diodes are encased in the knife edge array which is sealed. And on top of that the fans are pushing air AWAY from the diodes. There is no way smoke would be getting anywhere near these diodes. Also the beam would be so defocused and diffused if it just happened to be focused back at the diodes it would be nothing more than what and diode is normally exposed to.

Click to expand...

Unless the internal of these projectors subject them to highly reflective aluminum and ample amounts of smoke, then id say they are indeed subjected..

Did you test each LD before and after? to see if a possible increased level of optical flux within the cavity of each LD for certain did no damage? You are simply assuming that it did not.

You are selling these under the assumption to most that they were removed from an unused projector. In this case yes I would rather buy from the other member...

I will be stripping another projector in the next day or two and will be sure to test the heat experienced by the array, as this is something I have not tested.. so no opinion here. But logic tells me that those 3 high output fans are sitting in front of the heatsink FOR A REASON.

I know for damn sure I will not run any array like this and just hope that nothing is happening, then proceed to sell them as new.

Just my 2 cents..


BTW, these 'sleds' are not sealed air tight... smoke gets everywhere.


*EDIT

LMAO "Don't try to lecture me on something you obviously know nothing about" - thanks for the neg rep :beer:


You plopped the diode array on the projector, defeated the safety switch... You sir, are a master!!

The comment you made...

Pontiacg5 said:

But you know everything because you made a HeNe laser (oh wow! you can hook two wires up to a glass tube!)

Click to expand...

has been reflected by your own noob attempt at an array..

In your case>

'But you know everything because you made a laser. (oh wow! you can plug the power cord into the outlet!!'

Good thing you can buy lasers that are already built :san: And at the expense of others to boot.

I'm just curious as to two things. The first of which is.. how is running the LD block of a casio projector at the same power levels it's run in in the projector.. which is either 1.6W or 1.8W pulsed.. I can't remember which... with the stock cooling, any worse than how it's operated inside the projector? Doesn't seem to me like it's doing any more harm than the guy who said he watched a movie on his before he gutted it and sold the diodes.

The second thing i'm interested in knowing is how many of these projectors wannaburn has dismantled so far?

Come on Dudes I have respect for both of You, so Don't do a Tit for Tat war in an open Thread.:spank:

qumefox said:

I'm just curious as to two things. The first of which is.. how is running the LD block of a casio projector at the same power levels it's run in in the projector.. which is either 1.6W or 1.8W pulsed.. I can't remember which... with the stock cooling, any worse than how it's operated inside the projector? Doesn't seem to me like it's doing any more harm than the guy who said he watched a movie on his before he gutted it and sold the diodes.

The second thing i'm interested in knowing is how many of these projectors wannaburn has dismantled so far?

Click to expand...

Ill be opening my 4th box after im done with the last few in my tray.

How is it worse? The gamble that is taken with other peoples $$$.

A guy who watches a movie on it, is using it as Casio designed it to run.
If there werefailure issues with it, consumers would be reporting that they crap out far
earlier than the expected lifetime. Taking it apart and running it at full with
little to no cooling as seen in the vid is what caught my attention.

My beef was with the fact that the video and who knows what other experiments / runtimes, unaccounted by video, were performed with other members diodes.

If he bought the projector with his own cash, did the video, and messed anything up, it would be at his expense. Not at the members expense, who are waiting for their fresh diodes..


If he wanted to build an array based laser for himself, by all means, do what you must.
But I think its unfair to the members buying these as new if there is a chance of damage, or shortened life brought on by the actions of the GB host.

If im paying full price, I expect that at most the projector be powered, check the LD's, shut it of and get to work. This can be done at low output, not at its highest, again at
the discretion of the GB host.

Burning plastics and smoking up the area (unvented) for god only knows how long, cannot be good in the least.

If the members who bought these are fine with it, no probs. Its their money.

No case can be made in either direction IMHO, as no data was taken before nor after
running the array in this fashion.

The claim of lower temps in ambient air without the forced air through the fins, makes no sense to me at all.

The fans (3 of them) scream when running full. I dont think ive encountered fans that can move the volume they do in such a small package. If you sit one on the table and power it, the pressure they can generate will make the fan slide on the table! and thats just 1.
In comparison of having the array inside vs sitting on top, there is no way they are being fed the intended airflow, no matter what direction the air passes...

Just because the array has thermal protection only means there is a fail safe in place, it does not mean the diodes will go unscathed from being put into shutdown at full current.


All im saying is if I was in a GB and seen this video, knowing my 40$ LD was in there, I would not be pleased. If im paying full price, I want pristine condition parts like the GB before and after mine. I do not want to be the guy whos LD was featured in a youtube video and beyond. But again not my money, just my 2 cents...


In the GB for the 500mW reds on PL, how would you feel if the GB host was firing all the LD's to test, and while he was at it, burned a bunch of crap with them?

If your gonna 'play' with something, especially something as sensitive as an LD (in this case many of them), do it with your own.

If he had posted in his thread, 'hey guys got an idea while im testing your diodes', and EVERYBODY was fine by it, I would not have posted in the first place.

Im not saying all those LD's are crap now, just pointing out what I thought to be obvious.
But I still would not personally do this, and I dont think you will see any other GB runners doing the same... that is unless the LD's are theirs and they dont care, which we see people doing all the time to find the limits.. not just for the sake of the video.